Batch mode of reactions is followed widely, though conversion to continuous mode may be desirable in many cases. In batch mode of reactions, monitoring of reaction parameters such as heat transfer is carried out at the beginning and end of the reaction using batch mode calorimeters. Sampling during reaction is not possible.
Continuous flow synthesis has become an accepted approach for the synthesis of chemicals which were otherwise difficult to synthesize in conventional manner. The large heat transfer area per unit volume helps to carry out fast and exothermic reactions in a reliable manner. The same approach can be used to extract important features about the reaction viz. reaction rate constants, activation energy and also to some extent the thermodynamic parameters. However, to achieve this objective, it is necessary to have a compact and versatile device that can help to measure the reaction kinetics as well as heat of reaction in a quick manner.
Calorimeters that measure heat of reaction in batch reactions are marketed products. There are few reports in literature that attempt to measure heat of reaction and other thermokinetic properties in micro reactor based devices and processes and using LED display based calorimeters. But these prior art devices achieve measurement of thermokinetic properties at the beginning and end of reactions only, and are not designed to measure said properties in a continuous manner during the progress of a reaction.
WO2012097221 titled “System And Method For A Microfluidic Calorimeter” relates to a system for calorimetry comprising: a calorimetry apparatus comprising: a microfluidic laminar flow channel; at least two inlets in fluid connection with the laminar flow channel, the inlets allowing fluid to flow into the laminar flow channel; and a plurality of microscale temperature sensors disposed below the laminar flow channel at known positions relative to boundaries of the channel; and a processor in communication with the temperature sensors for calculating a calorimetry measurement based on local temperatures at the respective positions of the sensors in the channel derived based on data output by the microscale temperature sensors. The temperature sensors are nanohole arrays in a metal layer disposed below the laminar flow channel. But the drawback of this system is that it does not provide the extent of reaction progress at the point at which temperature is measured.
US2013121369 titled “Adiabatic Scanning Calorimeter” relates to an adiabatic scanning calorimeter for simultaneous measurements of the temperature dependence of heat capacity and enthalpy of liquids and solids and phase transitions, but the calorimenter does not have an option for monitoring the reaction and hence cannot be used to estimate the heat of reaction. It mainly functions as a temperature monitoring device. An article titled “Measuring enthalpy of fast exothermal reaction with micro-reactor-based capillary calorimeter” by K. wang, Y. C. Lu DOI: 10.1002/aic.11792 in AIChE Journal, Volume 56, Issue 4, pages 1045-1052, April 2010 discloses a new micro-reactor-based capillary calorimeter for the enthalpy measurement of fast exothermal reactions. The new calorimeter is operated in the continuous way. and the reaction enthalpy is measured with the online temperatures from detached sensor chips. A standard reaction system and an industrial reaction system are selected to test this new calorimeter with homogeneous and heterogeneous reaction processes. The measurement is taken at nearly adiabatic situations and the reaction enthalpy is calculated from the rising of temperature. High accuracy and good repeatability are obtained from this new calorimeter with relative experimental errors less than 3.5% and 2.4%, respectively. But this device may not be useful in isothermal conditions and the systems where phase change is possible. An other major drawback is that it does not track the reaction.
To overcome the drawbacks of the various cited devices and to provide a device which can be used as a flow reactor for synthesis and for discerning the reaction kinetics as well as as a flow calorimeter, the inventors disclose herein a calorimeter that functions as a device to measure reaction kinetics, preferably heat of reaction in a continuous manner, in adiabatic as well as in isothermal conditions. The device can be used independently for each of the above or simultaneously for any two or all of them together. Further, while the cited devices may measure the heat of reaction, none of the prior art devices can monitor the progress of the reaction continuously, which is necessary for the accuracy in the estimation of heat of reaction/dilution/dissolution/quenching With or without phase change during the reaction etc.